Pseudo random code sequences, also known as pseudo random noise codes (PRNC) or pseudo random number (PRN) codes, are used for radio transmission, for example. The codes are spread codes that prompt frequency spreading for an information signal. The wideband transmission means that such a signal has a high level of robustness toward interference. By way of example, spread sequences are used in satellite navigation systems such as GPS, Glonass, Beidou or Galileo. In this case, the received satellite signal is situated below a noise level. A receiver is capable of detecting and decoding the emitted signal only via correlation with an appropriate PRN code that the receiver itself has available. This is normally the identical PRN code that may already be available in the receiver, for example. It is also possible to refer to a replica PRN code, which is a reconstructed or simulated PRN code or a PRN code available as a second version.
Cryptographic PRN codes have been used. In this case, the code sequence is produced on the basis of a cryptographic key. A receiver is capable of generating the appropriate PRN code for decoding the received signal only if the receiver knows the PRN code used by the transmitter for transmitting the signal. For this, the receiver needs the cryptographic key.
The receiver, above all the signal processing on the receiver, needs to be protected against attackers by security mechanisms in complex fashion in this case. By way of example, an field programmable gate array (FPGA) on which the cryptographic signals are handled needs to be secured by emission protection or tamper-proofing in complex and hence expensive fashion.
Raw data has been digitized and recorded from a received GPS signal. The raw data is transmitted to a cloud service, so that the signal processing is performed on a server. The server is protected in a special way in this case, so that the security-critical cryptographic signal processing takes place in a secure computer center. However, this requires a large proportion of the server environment, including data transmission paths used, to be protected, again in complex fashion.